Airplane control



Feb. 13, 1940. I. I. SIKORSKY 2,1

AIRPLANE CONTROL Filed D ec. 22, 1937 I 2 Sheets-Sheet 1 INVENTOR. @UPISFKDPSK) *2 M ATTORNEY Feb. 13,1940. 7 l. l. SlKORSKY 2,190,340

AIRPLANE CONTROL Filed Dec. 22, 1937 2 sheetssneex 2 INVENTORQ 33 I I [901515)]? uralfy A TTORNEY Patented Feb. 13, 1940 AIRPLANE ooN'rnoL Igor IhSikorsky, Trumbull, Conn, assignor to United Aircraft Corporation, East Hartford, Conn., a corporation of Delaware Application December 22, 1937, Serial No. 181,173

6 Claims.

This invention relates to improvements in aircraft control means and has particular reference to an improvement in servo-mechanisms for moving or operating under control of the pilot or for assisting the pilot of an aircraft in manipulating or operating one or more of the aircraft flight control surfaces, lift increasing devices, the landing gear or any other movable or operable instrumentality forming a part of or carried by the aircraft.

An object of the invention resides in the provision of an improved servo-mechanism driven by the relative wind of flight of the aircraft when operative, and producing only negligible drag increase when inoperative.

A further object resides in the provision of" an operative connection for a servo-mechanism of the character described, so arranged that the' servo-mechanism may be used to move or assist in moving or operating one or more of the above mentioned instrumentalities forming a part of or carried by the aircraft or' may be entirely disengaged from the manual controls for moving or operating such instrumentalities.

A still further object resides in the provision of -a servo-mechanism of the character indicated, so constructed and arranged that the instrumentality or instrumentalities to which it is connected may be moved or operated by a manually operable pilot or pencil type control.

Other objects and advantages will be more particularly pointed out hereinafter or will become apparent as the description proceeds.

In the accompanying drawings in whichlike reference numerals are used to designate similar parts throughout, there is illustrated, in two somewhat modified forms, a'suitable embodiment of what is now considered to be a preferred application of the invention. The drawings, however,

'= are for'the' purpose of illustration only and are not to be taken as limiting orgrestricting the scope of the invention.

In thedrawings, Fig. 1 is a somewhat schematic sidexelevational' view 01' a fragmentary. portion of an airplane control mechanism showing a servo-mechanism constructed according to this invention applied thereto.

Fig. 2 is anend elevational view of the servomechanism illustrated in Fig. 1, and 0 Fig. 3 is a somewhat schematic illustration of a modified form of control mechanism utilizing a 1 and 2. 4 Referring to the drawings in detail, the aircraft,

' trols the ailerons and the elevators and the rudder is moved by means of a rudder bar or a pair of servo-mechanism of the form illustrated in Figs.

a fragmentary portion of which is generally in dicated by the numeral in, may be provided with the conventional control surfaces suchas ailerons on the Wings to control the lateral stability or rolling movements of the airplane, elevators on the tail group or empennage at the rear of the airplane to control the vertical stability or pitching movements of the airplane, and a rudder,

also on the tail group or empennage, for controlling the directional stability of the aircraft. In the conventional aircraft these various control surfaces are connected for independent movement to manually operable controls. In the usual construction the control column l2 confoot-operated pedals l4, connected to the rudder by suitable means such as thecontrol cable, two portions of which are indicated at It and H3. The pilot seat is located in a position convenient to the control elements I2 and. and has disposed adjacent LAGIGtO other indicating and control instrumentalities necessary or convenient to the operation of the aircraft.

The servo-mechanism may comprise a winddriven motor, located in some position in which its vanes will be in the wind stream flowing past the aircraft, and a motion reducing gear connecting the wind-driven motor with the instrumentality to be moved or operated, or with the connection leading to such instrumentality. Obviously, such a servo-mechanism may be connected with any one of or any number of the control surfaces or other instrumentalities with which the aircraft is provided to assist the manual effort exerted by the pilot to move such control surface 35 or surfaces, or to itself move such surfaceor surfaces under pilot control.

In the form of the invention illustrated, the vanes, generally indicated at 22, each comprise a'relatively fixed member 24 and a relatively mov- 4D able member 26, which may be inclined in either direction with respect to the fixed member to impart to the wind-driven motor a rotation in either direction desired. When the movable portion is in alignment with the fixed portion in the direction of air flow, the motor will not rotate and will impose a minimum and negligible drag on the forward progress of the aircraft. The vanes are mounted upon a suitable rotatable shaft, as indicated at 28, and the movable "portions may be inclined with respect to the fixed portions bysuitable means such as the rod which extends through the hollow shaft 28 and is connected at one end by means of suitable links and levers 32 withthe movable vane portions :26

and has at its opposite end a rack and pinion posed between thertwo portions I6 and I6 of the control cable. The rack bar may be suitably supported for longitudinal movements by means of the spaced pairs of rollers 48 and 56 and the shaft 42 is preferably supported on a linkage arrangement including parallel co-extensive pairs of links 52, 54 and 56. A control rod 58 is connected to the pivotal connection between the pairs of links 52 and 54 so that longitudinal. movement of the rod 58 in one direction, for instance downwardly, will move the pinion out of mesh with the teeth on the rack bar 46, and movement of the control shaft in the other direction will restore the pinion to its meshing relation with the teethon the rack bar.

In the arrangement shown by way of example in Figs. 1 and 2 the servo-mechanism is arranged to assist in the control of the aircraft rudder. In this arrangement the control cable I6, leading from the foot pedals, passes over pulleys, one of which is shown at 66, 'each mounted upon a movable pivot carried by a lever as shown at 62, having a fixed pivotal connection at 64. The free ends .of the levers 62 are connected to the ends of a cable 66 which is operatively connected intermediate its length with the rack and-pinimi arrangement 34. Movements of the foot pedals I4 to control the aircraft rudder will exert a force on the pulleys 66 which will cause the levers 62. to swing. about their pivotal connections 64, applying a force to the cable 66 which in turn actuates the rack and pinion mechanism 34 and inclines the movable portions 26 of the wind motor vanes with respect to the fixed por- I tions 24. The wind motor 22 thereupon starts to rotate and its force is added to the manual efi'ort exerted upon the pedals I4 by reason of the connection through the sprockets 36 and 38 and the rack and pinion device including the elements 44 and 46.

At times it may become desirable to discontinue the operation. of the servo-motor and rely entirely upon manual effort to control the aircraft. At such times it is also desirable to completely free the manual control mechanism from the wind-driven servo-mechanism' so that the manual effort exerted upon the control surfaces will not be diminished by an amount necessary to move the servo-mechanism or by friction in the servo-mechanism connection. For this purpose there is provided a manually controllable lock-out mechanism including the manually operable lever 66 located in a position convenient to the pilot seat 26 and connected by suitable' means, such as the link 16, with cam members 12 mounted on fixed pivots I4 and shaped, when in one position, to bear agaiiis't the levers 62 and restrain the levers against movement. The link 16 is also connected through an additional link I6and bell crank lever I6 with the rod 56 so that movement of the manual lever 68 will lock the levers62 in fixed position and simultaneously move the pinion 44 out of mesh with the teeth on the rack bar 46 thereby entirely freeing, the manual'control from the servo-mechanism. The

[8. manual lever 68 has two operative positions in either of which it may be locked by suitable means such as the toothed quadrant 66. and latch mechanism 82. y

In the somewhat modified form of the Invention illustrated in Fig. 3 provision has been made for a form of manual control usually referred to as a pilot or pencil type control. In this arrange-. ment when the manual lever 66 is in the position illustrated in Fig. 3 of the drawings, the control may be the samefas that illustrated in Figs. 1 and'2 when-the servo-motor is operatively connected into the control mechanism. Under these conditions tension on either of the cables I6 will act on the respective one of the'pulleys 66 to swing the associated lever 62 to move the control cable 66 to actuate the wind-driven servo-motor in the proper direction of rotation. In this form of the device the cable 66 is divided into two parts, a second part of which has been indicated at 86 in Fig. 3. The cable portion 86 is led over additional pairs of pulleys 66, 66, 62, 64 and 66 and has its ends connected to the free ends of the levers 62 and its mid-portion wound upon a drum 66 carried by the pencil control mechanism generally indicated at I66. The pulleys 64 are carried upon respective pivots located intermediate the length of respective lever members I62. one end of each of which is pivoted on a fixed support I64 and the other end connected to tl1e,re-. spective end of the control cable 66. When the manually controlled lever 68 is in the position illustrated, a pivoted lever member I66, connected at its free end to an intermediate part in the length of the cable 66; is restrained against rotation about its pivotal mbunting I66 by means of a lock I I6 operatively associated with the handle 66 so that the cable 86 cannot move. Under these conditions movement ofthe levers 62 will impose a reactive force between the respective pairs of pulleys 96 and 64 causing the pulleys 64 to move and to thereby move the cable 66.

When the manual lever 66 is moved to. the opposite side of its quadrant 86, the lever I66 is released and the cams 12 are moved to lock the respective levers 62 against movement. Under these conditions movement of the pencil or pilot control I66 will move the cable 66 and, since the ends of the'cable 86 connected to the levers 62 are fixed, .will impose a reactive force between the pairs of pulleys 64 and 62 therebymoving the pulleys 64 and the" cable '66 to actuate the servo-mechanism. With the arrangement illustrated in Fig. 3' the control'may be either by the usual manual-controlassistedby the servomechanism or may be alternatively by the servomechanism under the control of the pilotor pencil control device or by the manual control alone when the pilot control is operative but not utilized. In the latter case the pencil control will he usually fixed in its neutral position by some adequate mechanism.

Inthe arrangement shown in Fig. 3 the ,direct manual control may be entirely omitted and the pencil control alone relied upon formoving or operating the particular instrumentality through the medium of the servo-mechanism. In such an arrangement it would. in many cases, be desirable to mount the servo-mechanism. on or closely adjacent to the instrumentality to be moved or operated and to connect the servomechanism to the instrumentality by means of a relatively short .irreversable drive. Only a very light connection would then be necessary between the pencil. control and the servo-mcha nism.

' a,1 eo, 4o While there has been illustrated and described in two somewhat modified constructional em- Patent is as follows:

bodiments a suitable application of' the idea of the invention, it.is to be understood that theinvention is in no way limited to the constructional form's so illustrated and described but that such changes in the size, shape and arrangement- 1. In combination with a vehicle provided with movable control instrumentalities and movable through the air at a speed sumcient to drive a wind-motor, a wind-driven servo-mechanism'for operatiwely moving one or more of said instrumentalities, means actuated by manual effort for operatively moving the same instrumentalities, pilot means for controlling said servo-mechanism, an operative connection between said manually actuatable means said servo-mechanism and the control instrumentalities \movable thereby efv fective to actuate said servo-mechanism to assist the manual eflort applied to said manually actuatable means to move said instrumentalities, and selective means effective to disruptthe operative connection between said manually actuatable means and said servo-mechanism to render said control instrumentalities movable by manual e1- fort exclusively or'movable by said servo-mechanism exclusively under control of said pilot means. J

2. -In an aircraft having a movable control surface, manuallyactuatable means for moving said control surface, a wind-driven servo-mech-. anism, a connection between said servo-mechanism and said manually actuatable means for applying power developed by said servo-mechanism to move said control surface, means for moving the vanes 'of said servo-mechanism to render the same operative, and manually controllable means for disrupting said connection and locking said vane moving means while leaving said manually actuatable means free to move said control surface.

3. In an aircraft having a movable control surface, manually actuatable means for moving said control surface, a wind-driven servo-mechanism, a connection between said servo-mechanism and said manually actuatable means for applying y 3 .power developed by said servo mechanism to move. said control surface, manually operable pilot means for actuating said servo-mechanism to move said control surface in either direction, and to a desired extent, and manually cont-rollable means for rendering said pilot means operative or inoperative.

4. In an aircraft having a movable flight con- 1 trol element, manually actuatable means for moving said element by the application of manual effort, a controllable wind-driven servo-motor, a connection between said servo-motor and said manually actuatable means for applying the power developed by said servo-motor to assist said manual effort, a second connection between s'aid manually actuatable means and said servomotor to control said servo-motor inaccordance with the application of manual effort to said manually actuatable means, a manually operable pilot control associated with said second connection, and manually controllable means for chang-' ing the operation of said second: connection to cation of manual effort to said manually actuatable-means to apply thee-power developed-there by to assist said manual efiort, and manually controllable means for locking said servo-motor against rotation with said blades in their mini-.

mum drag position.

6. In an aircraft having a movable flight con trol element, manually actuatable means for moving said element by the application of manual eifort, a wind-driven servo-motor controlled by the application of manual effort to said manually actuatable means to apply the power developed thereby to assist said manual efiort, and

a manually operable pilot control for controlling said servo-motor independently of said manually actuatable means to move said flight control element entirely by the power developed by said servo-motor.

' IGOR I. SIKORSKY. 

